One characteristic of the developing bovine pituitary is that the contents and concentrations of five hormones (prolactin--PRL, growth hormone --GH, luteinizing hormone--LH, follicle-stimulating hormone--FSH, and thyroid-stimulating hormone--TSH) are strikingly diverse and can vary as a function of both gestation and sex. This developmental variation in the level of the pituitary hormones could be a reflection of unique rates of synthesis, degradation, and secretion which change as development ensues. Different rates in hormone synthesis may be due to differential expression of the genes which code for these pituitary proteins. As a result, our working hypothesis is that changes in glandular concentration of pituitary hormones, at some points in development, are results of changes in the concentration of their respective mRNAs. Therefore, the objective of this project is to provide an ontological description of the steady-state levels of the mRNAs which code for bovine PRL, GH and the common alpha and different beta subunits of LH, FSH and TSH. This description will reveal when in development the changes in the levels of hormone-specific mRNA occur, and whether these changes in mRNAs coorelate with the known changes in the concentrations of their respective proteins. The long-range goal of this study is to correlate the developmental changes in one of the pituitary glycoprotein hormones with the numerous steps involved in the biosynthesis of the mRNAs which code for the corresponding alpha and beta subunit proteins. Thus the ontological description obtained in this study will prove useful in selecting a specific, developmentally regulated alpha and beta mRNA for further study.